The Organic Light Emitting Display (OLED) device possesses many outstanding properties of self-illumination, low driving voltage, high luminescence efficiency, short response time, high clarity and contrast, near 180 degrees view angle, wide range of working temperature, applicability of flexible display and large scale full color display. The OLED is considered as the most potential display device.
The OLED can be categorized into two major types according to the driving ways, which are the Passive Matrix OLED (PMOLED) and the Active Matrix OLED (AMOLED), i.e. two types of the direct addressing and the Thin Film Transistor matrix addressing. The AMOLED comprises pixels arranged in array and belongs to active display type, which has high lighting efficiency and is generally utilized for the large scale display devices of high resolution.
The OLED element generally comprises a substrate, an anode located on the substrate, a Hole Injection Layer located on the anode, a Hole Transporting Layer located on the Hole Injection Layer, an emitting layer located on the Hole Transporting Layer, an Electron Transport Layer located on the emitting layer, an Electron Injection Layer located on the Electron Transport Layer and a Cathode located on the Electron Injection Layer. The principle of the OLED element is that the illumination generates due to the carrier injection and recombination under the electric field driving of the semiconductor material and the organic semiconductor illuminating material. Specifically, the Indium Tin Oxide (ITO) electrode and the metal electrode are respectively employed as the anode and the cathode of the Display. Under certain voltage driving, the Electron and the Hole are respectively injected into the Electron and Hole Transporting Layers from the cathode and the anode. The Electron and the Hole respectively migrate from the Electron and Hole Transporting Layers to the Emitting layer and bump into each other in the Emitting layer to form an exciton to excite the emitting molecule. The latter can illuminate after the radiative relaxation.
With the development of display technologies, people are pursuing larger screens, higher resolutions, and more stimulating visual effects. This poses higher requirements for the manufacturing process, materials, and processes of the panels. The large-sized OLED displays possessing better visual experience have become a major trend in the future. However, the larger the size of the OLED display is, the higher the power consumption of the display becomes, which affects the quality of the product.